fix(CI): Suppress psalm UndefinedClass

Signed-off-by: Joas Schilling <coding@schilljs.com>

lib/private/Files/Storage/Local.php

@@ -558,6 +558,7 @@ private function calculateEtag(string $path, array $stat): string {
 	}
 
 	private function canDoCrossStorageMove(IStorage $sourceStorage) {
+		/** @psalm-suppress UndefinedClass */
 		return $sourceStorage->instanceOfStorage(Local::class)
 			// Don't treat ACLStorageWrapper like local storage where copy can be done directly.
 			// Instead, use the slower recursive copying in php from Common::copyFromStorage with